Desenare linie folosind algoritmul Bresenham

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#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>
#include <iostream.h>
#include <math.h>
#include <dos.h>
//#include <mouse.h>

void Bresenham(const int x_1,const int y_1,const int x_2,const int y_2)
    {
       int color=getcolor( );

       int x1=x_1;
       int y1=y_1;

       int x2=x_2;
       int y2=y_2;

       if(x_1>x_2)
   {
      x1=x_2;
      y1=y_2;

      x2=x_1;
      y2=y_1;
   }

       int dx=abs(x2-x1);
       int dy=abs(y2-y1);
       int inc_dec=((y2>=y1)?1:-1);

       if(dx>dy)
   {
      int two_dy=(2*dy);
      int two_dy_dx=(2*(dy-dx));
      int p=((2*dy)-dx);

      int x=x1;
      int y=y1;

      putpixel(x,y,color);

      while(x<x2)
  {
     x++;

     if(p<0)
        p+=two_dy;

     else
        {
    y+=inc_dec;
    p+=two_dy_dx;
        }

     putpixel(x,y,color);
  }
   }

       else
   {
      int two_dx=(2*dx);
      int two_dx_dy=(2*(dx-dy));
      int p=((2*dx)-dy);

      int x=x1;
      int y=y1;

      putpixel(x,y,color);

      while(y!=y2)
  {
     y+=inc_dec;

     if(p<0)
        p+=two_dx;

     else
        {
    x++;
    p+=two_dx_dy;
        }

     putpixel(x,y,color);
  }
   }
    }

int main(void)
{
   int gdriver = DETECT, gmode, errorcode;
   int xmax, ymax,y,x;

   initgraph(&gdriver,&gmode,"");

   errorcode = graphresult();
   if (errorcode != grOk)
    {
      printf("Graphics error: %sn", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1);
    }

xmax = getmaxx();  ymax = getmaxy();
//MouseInit();
//MouseShow();
Bresenham(100,100,200,0);
Bresenham(100,100,200,20);
Bresenham(100,100,200,40);
Bresenham(100,100,200,60);
Bresenham(100,100,200,80);
Bresenham(100,100,200,100);
Bresenham(100,100,200,120);
Bresenham(100,100,200,140);
Bresenham(100,100,200,160);
Bresenham(100,100,200,180);
Bresenham(100,100,200,200);

Bresenham(100,100,0,0);
Bresenham(100,100,0,20);
Bresenham(100,100,0,40);
Bresenham(100,100,0,60);
Bresenham(100,100,0,80);
Bresenham(100,100,0,100);
Bresenham(100,100,0,120);
Bresenham(100,100,0,140);
Bresenham(100,100,0,160);
Bresenham(100,100,0,180);
Bresenham(100,100,0,200);

Bresenham(100,100,100,0);
Bresenham(100,100,100,200);

//line(0,0,600,800);

//getch();
//closegraph();
//clrscr();
//getch();
//cout<<xmax<<"n";
//cout<<ymax;
getch();
return 0;
}